This application is a continuation of International Patent Application No. PCT/EP01/03813, filed Apr. 4, 2001. Priority is claimed based on Federal Republic of Germany patent Application No. DE 100 18 523.1, filed Apr. 13, 2000, the entire disclosure of which is hereby incorporated herein by reference.
The invention relates to a disk brake with a brake lining holding device for a brake lining which can be applied in the direction of a brake disk. The brake lining has a lining supporting plate with a brake lining material arranged thereon. A stop is provided for limiting the adjusting path of the brake lining. The invention also relates to a brake lining for such a disk brake.
A disk brake of this type is known from British Patent Document GB 1470919. In the case of the disk brake disclosed in this document, the caliper section carrying the rim-side brake lining is impacted when the wear limit of the lining has been reached.
This takes place because, in the case of sliding-caliper or fixed-caliper disk brakes of the known constructions, there is the problem that, when the wear of the brake lining and/or the brake disk is excessive, the brake lining is displaced so far in the direction of the brake disk that there is no longer a sufficient overlap of the brake lining with the supporting surfaces of the caliper or brake anchor plate and, during the operation of the brake, the brake lining is pulled into the gap between the brake lining holding device of the caliper or brake anchor plate and the brake disk.
The results of such a fault may be serious. Thus, the clamped-in brake lining may lock up the wheel during the drive, which may result in damage to the tire and the axle. According to the finding of the invention, this fault will occur particularly when influences exist which cause a very non-uniform wear between the two brake linings so that the critical wear condition of one of the two brake linings will occur unexpectedly early for the operator of the vehicle. Such influences may, for example, be considerable accumulations of dirt on only one of the two brake disk friction surfaces or a sluggish sliding guidance of a sliding caliper disk brake.
The early wear of an individual lining is particularly problematic when wear monitoring systems do not indicate this condition in time.
Measures are known for preventing the excessive wear which, however, do not have a sufficient effect and/or unacceptably impair the effect of the brake in emergency braking situations.
Thus, for example, the excessive wear of the outer brake lining in the case of sliding caliper disk brakes can be avoided in that, when the limit wear condition is reached, the slidability of the caliper is limited by a stop. This solution for the outer brake lining is implemented in series production, for example, in the case of sliding caliper disk brakes of Knorr-Bremse Systems for Commercial Vehicles with the commercial designation of SB Series (for example, SB6000, SB7000).
Another possible measure is a limitation of the adjusting rotation movement of the threaded spindles of the wear adjusting system. As a result, it can be avoided that the total wear of both brake linings together exceeds a permissible value. When a high non-uniform wear occurs, this measure is, however, not effective for the brake lining with the most extensive wear.
It has also been suggested to construct the axle-fixed brake lining holder such that the application force of the caliper is absorbed by the brake lining holder when the critical wear condition is reached and the brake linings are no longer brought in contact with the brake disk. However, this suggestion results in the problem of the reduction or of the complete failure of the braking effect in the event of an emergency braking (see, for example, German Patent Document DE 198 23 034 C1).
Based on the above-mentioned prior art, the invention relates to the problem of further developing a disk brake of the above-mentioned type such that a reliable wear adjusting limitation is implemented for the brake linings without the danger that the braking effect of the disk brake is significantly reduced in emergency situations.
The invention achieves this goal by providing a disk brake with a brake lining holding device for a brake lining which can be applied in the direction of a brake disk and has a lining supporting plate and a brake lining material arranged thereon. A stop is provided for limiting the adjusting path of the brake lining. The stop is elastically and/or plastically deformable under the effect of a given brake application force which can be generated by the disk brake for limiting the adjusting path of the brake lining. Accordingly, the stop for limiting the adjusting path of the brake lining is elastically and/or plastically deformable under the effect of a given brake application force which can be generated by the disk brake.
The invention also provides a particularly advantageous brake lining for use in a disk brake, particular a disk brake according to the invention. Accordingly, the brake lining has a projection or a recess for the interaction preferably with a recess or a projection—with the disk brake, so that a stop is formed between the brake lining and the disk brake. This stop can be elastically and/or plastically deformed when a limit application force is exceeded. The stop can also be formed in that only the brake lining has a projection which limits the displacement path of the brake lining support.
It is essential to the invention that an elastically or plastically deformable element is constructed either at the brake lining (support) and/or at the remaining disk brake or its lining holding device—for example, implemented at the caliper or at the brake anchor plate. This element is constructed such that, although it limits the adjusting path of the brake lining per se, it yields when a limit force is exceeded so that, at high braking forces, despite largely worn linings, a braking can still take place by means of the corresponding brake lining.
According to the invention, when the limit wear condition has been reached, the brake linings, by means of their lining supporting plate, come in contact with the stop—for example, at the axle-fixed brake lining holding device, by means of which contact, a further displacement of the brake linings is prevented for a given amount of the brake operating force. When this given operating force is exceeded, however, by means of the elastic and/or plastic deformation of the supporting elements at the brake lining or the brake lining holding device, an additional displacement path is opened up and thus an additional wear of the respective brake lining can occur for implementing at least one emergency braking operation.
Thus, in the invention, a disk brake and a brake lining particularly suitable for this disk brake are provided which, by means of simple constructive measures, are designed for avoiding, when the limit wear condition of one or both brake linings has been reached, the further wear of already worn brake linings during usual adaptation brakings. Nevertheless, in the event of an emergency braking, even the already worn brake linings are brought in contact with the brake disk for generating a sufficient braking effect.
According to a particularly preferred embodiment of the invention, the stop is designed such that, when a first given limit brake application force is exceeded, it is first elastically deformable and then, when a second higher limit brake application force is exceeded, it is plastically deformable.
Cost-effective constructive variants of the invention are formed in that:
a) the stop at the brake lining holding device of a sliding caliper disk brake has at least one recess on the brake anchor plate;
b) or that the stop at the brake lining holding device of a fixed caliper disk brake has a recess formed at the caliper,
c) in which recess at least one projection of the brake lining support engages which, when the limit brake application force is exceeded, is elastically and/or plastically deformable.
Depending on the design of the disk brake and the pertaining linings, it is basically contemplated that the at least one projection is constructed in one piece with the brake lining support, or is constructed as a separate element, which can be connected with the lining supporting plate.
According to a preferred variant of the invention which makes the production of the brake lining support only insignificantly more expensive, the at least one projection is constructed as the end of a bendable tongue which is molded or fitted to the brake lining support. Preferably, one of the bending tongues, respectively, is arranged relative to the brake disk rotating direction in the inlet and/or outlet area of the brake lining support. In addition, the recesses in the caliper or the brake lining support have a depth such that, when the limit wear condition is reached, a stop is formed for the projections of the lining supporting plate.
It is also contemplated that the at least one stop on the brake lining supporting surfaces of the brake lining holding device comprises molded-on or attached elements which are constructed in one piece with the brake lining holding device or are connected with it.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompany drawings.